Every study supported by the Center for Voice and Speech Communication involves the assessment of dynamic phenomena. Assessment techniques of these phenomena are continually being refined and improved; however, we find that descriptive summaries and statistical analyses in the literature compromise the wealth of information being gathered. The projects in this Center grant will obtain vast amounts of information, which we do not intend to compromise due to limitations in previously available summary measures or statistical methods. Recent developments in statistical theory and corresponding computer software have dramatically changed our ability to analyze data in a manner consistent with the objectives and hypotheses of research studies. Thus, in a manner consistent with the objective: to provide statistical results which directly address the specific aims of he individual projects. To meet this objective we have three specific aims: 1) to consult with investigators about their objectives and hypotheses to determine how they can best be met with respect to study design, data management, and statistical analyses, 2) to obtain and prepare complete and valid data for analyses, 3) to perform and summarize statistical analyses, and 4) to monitor surgical clinical trials. We will form a team for each specific project. Each team will consist of at least one statistician, a programmer, and, as required, an epidemiologist. The team will meet with the investigators during the planning stages and implementation of the study. The meetings will be to assure that the first three specific aims of the Biostatistics Core are met. The programmers will work directly with the project investigators to refine data collection techniques and to edit and summarize the data according to protocol. The epidemiologist will be consulting the projects with respect to epidemiologic methods, such as study design, assessment of risk profiles, and interpretation and extrapolation of results. The statisticians will assure that the advances in assessment techniques are exploited with the ongoing advances in statistical techniques and will prepare reports which permit easy understanding of the results and the methods.